<title>Three-dimensional nanomodification with ultrafast pulse laser</title>

Abstract

Various structures can be produced at the focal point inside a transparent material by using pulsed laser operating at the non-resonant wavelength with pulse widths of the order of femtoseconds. We have succeeded in the three-dimensional structural-phase transformation from diamond to amorphous structures which have high electrically conductive properties by the femtosecond laser pulses irradiation. The spatially periodic conductive structures indicate photonic crystal properties in terahertz region. We have also demonstrated the three-dimensional nanostructuring inside a glass material by the single femtosecond laser beam irradiation. The self-organized sub-wavelength periodic nanostructures are created by a pattern of interference between the incident light field and the electric field of the bulk electron plasma wave excited via two plasmon parametric decay. More recently, we have observed metallic Cu nanowires with a length of 1.0 μm and a diameter of 85 nm which were successfully photo-converted from commercial scale-like Cu particles, dispersed in a methanol solution, by using femtosecond laser irradiation. The growth mechanism of Cu nanowires under laser irradiation was suggested to be a nucleation growth process.